Segregation has been widely studied as a cause of educational and socioeconomic inequities in American society. However, few studies have sought to quantify the degree of segregation that exists within individual health care markets, and virtually no studies have examined the impact of segregation on racial disparities in health care. This study will examine the link between segregation in health care markets and disparities in health care delivery for black and white patients with acute myocardial infarction (AMI), a condition for which there exists substantial evidence of racial disparities. The specific aims are to: 1. Determine relationships between segregation and racial disparities in the use of coronary revascularization after acute myocardial infarction. 2. Determine relationships between segregation and racial disparities in mortality and readmission for acute coronary syndrome in patients with acute myocardial infarction. 3. Determine relationships between segregation and racial disparities in access to high quality hospitals. The 24-month study will analyze existing data for Medicare patients admitted for AMI to non-federal hospitals during a 10-year period from 1993 through 2002. The study will measure segregation in health care markets using two validated methods that have been widely used in sociology and will evaluate relationships between the segregation measures and racial disparities in the endpoints described above. Additional analyses will examine changes in segregation over time within individual markets and relationships between segregation and other health care market characteristics. The knowledge gained from this study about the significance of segregation as a determinant of racial disparity will be essential for designing effective strategies for eliminating disparities. [unreadable] [unreadable] [unreadable]